Information processing apparatus, information processing method, and program for the same

ABSTRACT

An FET is turned ON with supply of a power Vcc to a sensor started, and a signal indicating a result of detection is inputted from the sensor to a GPI terminal of an MCU. After supply of the power Vcc to the sensor is started, the MCU enters the sleep state, and the state is maintained until a normal detection result is outputted from the sensor. When the sensor starts outputting a normal detection result, the MCU returned from the sleep state upon an interruption by a timer, and sampling is made for an output from the sensor. When sampling is performed, supply of the power Vcc to the sensor is stopped with the CMU set in the sleep state. The present invention can be applied to a portable type of information processing apparatus such as a mobile telephone and a PDA.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Division of and is based upon and claims thebenefit of priority under 35 U.S.C. §120 for U.S. Ser. No. 11/092,542,filed Mar. 28, 2005, and claims the benefit of priority under 35 U.S.C.§ 119 from Japanese Patent Application No. P2004-096155, filed Mar. 29,2004, the entire contents of each which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to an information processing apparatus, aninformation processing method, and a program for the same, and morespecifically to an information processing apparatus and an informationprocessing method enabling reduction of power consumption and to aprogram for the same.

In association with the for recent tendency for increasingly highersophistication of portable devices such as a PDA (Personal DigitalAssistants) or a mobile telephone, and some of the devices incorporatedtherein a plurality of sensors including a CCD (Charge Coupled Device),a GPS (Global Positioning System) sensor, a finger print detectionsensor and the like.

In the portable devices incorporating therein various types of sensorsas described above, it is necessary to supply a power not only to thesensors themselves, and also to a microcomputer sampling signalsoutputted from the sensors with a battery having a limited capacity.Therefore power saving in each sensor and in the microcomputer isespecially demanded.

Consequently, to reduce power consumption in each sensor, there has beenproposed the technique for stopping supply of a power to each sensorduring a period after the end of previous sampling until start of nextsampling.

Further to reduce power consumption consumed by a microcomputer, therehas been proposed the technique for setting the microcomputer in thesleep state in which power consumption is low, for instance, by stoppingclocking while each signal outputted from each sensor is being sampled.

Patent Document 1 discloses the technique for reducing power consumptionin each sensor by providing, separately from a CPU (Central ProcessingUnit), a standby control circuit for controlling ON/OFF of a power forthe sensor and intermittently running the sensor with the standbycontrol circuit. Also there has been disclosed the technique for settingcircuits in the CPU other than those for detecting input signals so thatpower consumption in the CPU can be reduced.

Patent Document 1:

Japanese Patent Laid-Open No. 2000-88605

In a case where sensors are run intermittently, however, in some typesof sensors, a normal result of detection cannot be outputted immediatelywhen power supply is started, and thus an erroneous value may beobtained as a result of sampling, which is disadvantageous.

Further when the state of a microcomputer is returned from the sleepstate to the normal state, sometimes the state switching can not beexecuted at a high speed, for instance, because a certain period of timeis required until PLL (Phase Lock Loop) of a memory used in themicrocomputer is stabilized, which is also disadvantageous.

In addition, when a sensor required executing sampling in a short cycleis used, a load to the microcomputer increases, which naturally resultsin increase of power consumption in the microcomputer.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of thecircumstances as described above. Accordingly, it is an object of thepresent invention to reduce power consumption.

A first information processing apparatus according to the presentinvention includes a detection unit for detecting a physical quantity asa target for detection; a first control unit for measuring the physicalquantity based on a result of detection by the detection unit and alsocontrolling supply of a power to the detection unit; and a first storageunit for storing therein a period of time after measurement of thephysical quantity by the first control unit is finished untilmeasurement for the physical quantity is carried out next as a standbyperiod with the first control unit shifted to the standby state duringthe period. Preferably, the first control unit can repeat the processingof starting supply of a power to the detection unit and then measuringthe physical quantity based on a result of detection by the detectionunit and the processing for terminating supply of a power to thedetection unit, shifting its own state to the standby state, andreturning from the standby state after passage of the standby period.

The first information processing apparatus according to the presentinvention may further include a second storage unit for storing thereindata indicating a physical quantity measured by the first control unit.In this configuration, the first control unit can supply a predeterminedquantity of data each indicating a physical quantity to the secondcontrol unit when the predetermined quantity of data each indicating aphysical quantity has been stored in the second storage unit.

The first information processing method according to the presentinvention is executed by an information processing apparatus including adetection unit for detecting a physical quantity as a target fordetection and a control unit for measuring the physical quantity basedon a result of detection by the detection unit and also controllingsupply of a power to the detection unit, and the method includes thestep of storing a period of time after measurement of the physicalquantity by the control unit is finished until measurement for thephysical quantity is executed next as a standby period with the controlunit shifted to the standby state during the period; and providingcontrols for repeating the processing of starting supply of a power tothe detection unit and then measuring the physical quantity based on aresult of detection by the detection unit and the processing forterminating supply of a power to the detection unit, shifting its ownstate to the standby state, and returning from the standby state afterpassage of the standby period.

A first program according to the present invention is a program to beexecuted by a computer for controlling an information processingapparatus including a detection unit for detecting a physical quantityas a target for detection and a control unit for measuring the physicalquantity based on a result of detection by the detection unit and alsocontrolling supply of a power to the detection unit, the programincluding the steps of storing a period of time after measurement of thephysical quantity by the control unit is finished until measurement forthe physical quantity is executed next as a standby period with thecontrol unit shifted to the standby state during the period; andproviding controls for repeating the processing of starting supply of apower to the detection unit and then measuring the physical quantitybased on a result of detection by the detection unit and the processingfor terminating supply of a power to the detection unit, shifting itsown state to the standby state, and returning from the standby stateafter passage of the standby period.

A second information processing apparatus according to the presentinvention includes a detection unit for detecting a physical quantity asa target for detection; a control unit for measuring the physicalquantity based on a result of detection by the detection unit and alsocontrolling supply of a power to the detection unit; and a storage unitfor storing therein a period of time after measurement of the physicalquantity by the first control unit is finished until measurement for thephysical quantity is carried out next as a standby period with thecontrol unit shifted to the standby state during the period. Preferably,the control unit can start supply of a power to the detection, shiftsits own state to the standby state, then returns from the standby stateafter passage of the standby period, and measures the physical quantitybased on a result of detection by the detection unit.

A second information processing method executed by an informationprocessing apparatus includes a detection unit for detecting a physicalquantity as a target for detection and a control unit for measuring thephysical quantity based on a result of detection by the detection unitand also controlling supply of a power to the detection unit, the methodincluding the steps of storing a period of time after supply of a powerto the detection unit is started by the control unit until a normalresult of detection by the detection unit is obtained as a standbyperiod with the control unit shifted to the standby state during theperiod; and providing controls for starting supply of a power to thedetection unit, shifting the control unit into the standby state,returning the control unit from the standby state after passage of thestandby period, and measuring the physical quantity based on a result ofdetection by the detection unit.

A second program to be executed by a computer for controlling aninformation processing apparatus including a detection unit fordetecting a physical quantity as a target for detection and a controlunit for measuring the physical quantity based on a result of detectionby the detection unit and also controlling supply of a power to thedetection unit, the program including the steps of storing a period oftime after supply of a power to the detection unit is started by thecontrol unit until a normal result of detection by the detection unit isobtained as a standby period with the control unit shifted to thestandby state during the period; and providing controls for startingsupply of a power to the detection unit, shifting the control unit intothe standby state, returning the control unit from the standby stateafter passage of the standby period, and measuring the physical quantitybased on a result of detection by the detection unit.

A third information processing apparatus according to the presentinvention includes a detection unit for detecting a physical quantity asa target for detection; a control unit for measuring the physicalquantity based on a result of detection by the detection unit and alsocontrolling supply of a power to the detection unit; and an estimationunit for estimating a normal result of detection by the detection unitobtained after passage of a predetermined period of time after supply ofa power to the detection unit is started based on a result ofmeasurement of the physical quantity by the control unit. Preferably,the control unit can start supply of a power to the detection unit,measures the physical quantity based on a result of detection by thedetection unit, and stops, when a normal result of detection isestimated by the estimation unit, supply of a power to the detectionunit.

The control unit can further stop supply of a power to the detectionunit and then shift the state of the unit itself to the standby state.

A third information processing method according to the present inventionis executed by an information processing apparatus including a detectionunit for detecting a physical quantity as a target for detection and acontrol unit for measuring the physical quantity based on a result ofdetection by the detection unit and also controlling supply of a powerto the detection unit, and the method includes the steps of estimating anormal result of detection by the detection unit obtained after passageof a predetermined period of time after supply of a power to thedetection unit is started based on a result of measurement of thephysical quantity by the control unit; and providing controls forstarting supply of a power to the detection unit, measuring the physicalquantity based on a result of detection by the detection unit, andstopping, when a normal result of detection is estimated by theestimation unit, supply of a power to the detection unit.

A third program according to the present invention is executed by acomputer for controlling an information processing apparatus including adetection unit for detecting a physical quantity as a target fordetection and a control unit for measuring the physical quantity basedon a result of detection by the detection unit and also controllingsupply of a power to the detection unit, and the program includes thesteps of estimating a normal result of detection by the detection unitobtained after passage of a predetermined period of time after supply ofa power to the detection unit is started based on a result ofmeasurement of the physical quantity by the control unit; and providingcontrols for starting supply of a power to the detection unit, measuringthe physical quantity based on a result of detection by the detectionunit, and stopping, when a normal result of detection is estimated bythe estimation unit, supply of a power to the detection unit.

A fourth information processing apparatus according to the presentinvention includes a plurality of detection units each for detecting aphysical quantity as a target for detection; and a control unit formeasuring the physical quantity based on a result of detection by one ormore first detection units among the plurality of detection units andalso controlling supply of a power to a second detection unit inresponse to a result of measurement of the physical quantity.

When supply of a power to the second control unit is started, thecontrol unit can further measure a physical quantity based on a resultof detection by the second detection unit.

The first detection unit may be designed to consume a power less ascompared to the second detection unit.

The control unit may be designed to control supply of a power to thesecond detection unit based on the priority of the second detection unitset according to a result of measurement of the physical quantity.

The control unit may be designed to determine its own operatingsituation from a result of detection by the first detection unit and setthe priority of the second detection unit so that higher priority is setfor the second detection unit more required to operate in the determinedsituation.

The second detection unit may be designed to include a first positioningunit for executing positioning outdoors, and a second positioning unitfor executing positioning indoors. In this configuration, the controlunit sets, when it is determined from a dose of ultraviolet raysmeasured based on a result of detection by the first detection unit thatthe control unit is present outdoors, higher priority to the firstpositioning unit as compared to that to the second positioning unit, andcontrols supply of a power to the first and second positioning units sothat positioning is executed only by the first positioning unit.

The control unit may be designed to control supply of a power to thefirst and second positioning units so that positioning is executed whena distance obtained by multiplying a speed measured based on a result ofdetection by the first detection unit by a cycle of positioning by thefirst or second positioning unit shows higher precision as computed tothat in positioning by the first or second positioning unit.

The control unit may be designed to control supply of a power to thefirst positioning unit so that positioning is executed by the firstpositioning unit when a change in humidity measured based on a result ofdetection by the first detection unit is over a predetermined thresholdvalue.

The first detection unit may be designed to include a first positioningunit for measuring illumination intensity and a second measuring unitfor measuring a dose of ultraviolet rays. In this configuration, thecontrol unit controls supply of a power to the second measuring unit sothat measurement of a dose of ultraviolet rays is executed by the secondmeasuring unit when illumination intensity over the predeterminedthreshold value is measured by the first measuring unit.

A fourth information processing apparatus according to the presentinvention further includes a storage unit for storing therein a periodof time after measurement of a physical quantity by the control unitbased on a result of detection by a third detection unit among theplurality of detection units is finished until measurement of thephysical quantity is executed next as a standby period with the controlunit shifted to the standby state during the period, and the controlunit may be designed to repeat the processing for starting supply of apower to the third detection unit and measuring the physical quantitybased on a result of detection by the third detection unit and theprocessing for stopping supply of a power to the third detection unit,shifting its own state to the standby state, and returning from thestandby state after passage of the standby period.

The fourth information processing apparatus according to the presentinvention further includes a storage unit for storing therein a periodof time after supply of a power to a third detection unit among theplurality of detection units is started until a normal result ofdetection by the third detection unit is obtained as a standby periodwith the control unit shifted to the standby state during the period,and the control unit may further be designed to start supply of a powerto the third detection unit, shifts its own state to the standby state,returns from the standby state after passage of the standby period, andmeasures the physical quantity based on a result of determination by thethird detection unit.

The fourth information processing apparatus according to the presentinvention further includes a storage unit for storing therein dataindicating the physical quantity measured by the control unit, and thecontrol unit may be designed to supply, when a predetermined volume ofdata indicating the physical quantity is obtained by the storage unit,the predetermined volume of data indicating the physical quantity toother control unit executing a predetermined processing.

A fourth information processing method according to the presentinvention is executed by an information processing apparatus including adetection unit for detecting a physical quantity as a target fordetection, and the method includes the step of providing controls formeasuring the physical quantity based on a result of detection by one ormore first detection units among the plurality of detection units andalso controlling supply of a power for a second detection unit accordingto a result of measurement of the physical quantity.

A fourth program according to the present invention is executed by acomputer for controlling an information processing apparatus including aplurality of detection units each for detecting a physical quantity as atarget for detection, and the program includes the step of providingcontrols for measuring the physical quantity based on a result ofdetection by one or more first detection units among the plurality ofdetection units and also controlling supply of a power for a seconddetection unit according to a result of measurement of the physicalquantity.

In the first information processing apparatus, method and program eachaccording to the present invention, repeatedly executed are theprocessing for starting supply of a power to the control unit andmeasuring a physical quantity based on a result of detection by thedetection unit and the processing of stopping supply of a power to thedetection unit, shifting the state of the control unit to the standbystate, and returning from the standby state after passage of the standbyperiod.

In the second information processing apparatus, method and program eachaccording to the present invention, after supply of a power to thedetection unit is started, the state of the control unit is shifted tothe standby state and then the original state is restored after passageof the standby period, and measurement of a physical quantity isperformed based on a result of detection by the detection unit.

In the third information processing apparatus, method and program eachaccording to the present invention, after supply of a power to thedetection unit is started, measurement of a physical quantity isperformed based on a result of detection by the detection unit, and whena normal result of detection is estimated by the estimation unit basedon a result of the measurement, supply of a power to the detection unitis stopped.

In the fourth information processing apparatus, method and program eachaccording to the present invention, measurement of a physical quantityis performed based on a result of detection by one or more firstdetection units among a plurality of detection units, and supply of apower to the second detection unit is controlled based on the priorityof the second detection unit set according to a result of measurement ofthe physical quantity.

With the present invention, power consumption can be reduced.

Further with the present invention, acquisition of an erroneous value asa result of sampling can be prevented.

Still further with the present invention, state transition can quicklybe performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example of configuration of aninformation processing apparatus in which the present invention isapplied;

FIG. 2 is a view showing an example of state transition in an MCU and asensor;

FIG. 3 is a block diagram showing an example of functional configurationof the MCU;

FIG. 4 is a sequence diagram for illustrating a sequence of operationsof the MCU, an FET, and a sensor;

FIG. 5 is a flow chart for illustrating the processing by the MCU in theRun state;

FIG. 6 is a flow chart for illustrating the processing of the MCU byexecuting an interrupt handler;

FIG. 7 is a view showing an example of temporal change of humidityoutputted by a humidity sensor;

FIG. 8 is a view showing another example of state transition in the MCUand a sensor;

FIG. 9 is a view showing the effect when the state transition shown inFIG. 8 is employed;

FIG. 10 is a block diagram showing another example of functionalconfiguration of the MCU;

FIG. 11 is a flow chart showing the processing by the MCU for estimatinga normal value for the sensor;

FIG. 12 is a block diagram showing another example of configuration ofthe information processing apparatus in which the present invention isapplied;

FIG. 13 is a view showing an example of state transition in the MCU, agyro, an acceleration sensor, and a GPS module;

FIG. 14 is a block diagram showing an example of functionalconfiguration of the MCU shown in FIG. 12;

FIG. 15 is a flow chart for illustrating the processing by the MCU forsensing the operating situation and controlling supply of a power Vcc toa sensor;

FIG. 16 is a flow chart showing another processing by the MCU forsensing the operating situation and controlling supply of a power Vcc toa sensor;

FIG. 17 is a view showing an example of an intermittent operation of theGPS module;

FIG. 18 is a flow chart for illustrating still another processing by theMCU for sensing the operating situation and controlling supply of apower Vcc to a sensor;

FIG. 19 is a block diagram showing still another example ofconfiguration of the information processing apparatus in which thepresent invention is applied;

FIG. 20 is a flow chart for illustrating the processing by a Sub MCUshown in FIG. 19;

FIG. 21 is a flow chart in succession to FIG. 20 for illustrating theprocessing by the Sub MCU shown in FIG. 19;

FIG. 22 is another flow chart in succession to FIG. 20 for illustratingthe processing by the Sub MCU shown in FIG. 19;

FIG. 23 is a view showing an example of an intermittent operation of anillumination sensor;

FIG. 24 is a flow chart for illustrating the processing by a Main MCUshown in FIG. 19; and

FIG. 25 is a block diagram showing an example of configuration of apersonal computer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are described below, and thecorrespondence between the inventions described in this specificationand the embodiments is as described below. The description is providedto confirm that embodiments supporting the inventions described inclaims respectively are described in this specification. Therefore, evenif there is any embodiment described in “Detailed Description of theEmbodiments” section but not described in this section, it does notalways mean that the embodiment does not correspond to any invention. Onthe contrary, even if there is any embodiment described in this sectionas one corresponding to any invention, it does not always mean that theembodiment corresponds only to the specific invention.

Further, descriptions in this section are not intended to include all ofthe inventions described in this specification. In other words,descriptions in this section do not deny presence of inventionsdescribed in this specification but not claimed in this patentapplication, namely inventions which may be applied as a dividedapplication, or added in amendment.

The information processing apparatus according to claim 1 includes adetection unit (for instance, sensor 3 in FIG. 1) for detecting aphysical quantity as a target for detection; a first control unit (forinstance, MCU 1 in FIG. 1 (Sub MCU 82 in FIG. 19)) for measuring thephysical quantity based on a result of detection by the detection unit(for instance, sampling by a sampling section 24 shown in FIG. 3) andalso controlling supply of a power to the detection unit (for instance,control of a power by a power control section 21 shown in FIG. 3); and afirst storage unit (for instance, a timer section 22 shown in FIG. 3)for storing therein a period of time after measurement of the physicalquantity by the first control unit is finished until measurement for thephysical quantity is carried out next as a standby period (for instance,sleep state) with the first control unit shifted to the standby stateduring the period. Therefore, the first control unit repeats theprocessing of starting supply of a power to the detection unit and thenmeasuring the physical quantity based on a result of detection by thedetection unit and the processing for terminating supply of a power tothe detection unit, shifting its own state to the standby state, andreturning from the standby state after passage of the standby period(for instance, information processing apparatus executing anintermittent operation together with an MCU 1 and the sensor 3 accordingto a sampling cycle).

The information processing apparatus according to claim 2 furtherincludes a second storage unit (for instance, a buffer 93 shown in FIG.19) for storing therein data indicating the physical quantity measuredby the first control unit. Therefore, the first control unit furthersupplies, when only a predetermined volume of data indicating thephysical quantity is stored in the second storage unit, thepredetermined volume of the data indicating the physical quantity to asecond control unit (for instance, a Main MCU 81 in FIG. 19).

The information processing method according to claim 3 is executed by aninformation processing apparatus including a detection unit (forinstance, the sensor 3 in FIG. 1) for detecting a physical quantity as atarget for detection and a control unit (for instance, the MCU 1 (a SubMCU 82 in FIG. 19)) for measuring the physical quantity based on aresult of detection by the detection unit (for instance, sampling by thesampling section 24 in FIG. 3) and also controlling supply of a power tothe detection unit (for instance, control of a power by the powercontrol section 21 in FIG. 3), and the method includes the steps ofstoring a period of time after measurement of the physical quantity bythe control unit is finished until measurement for the physical quantityis executed next as a standby period with the control unit shifted tothe standby state (for instance, sleep state) during the period (forinstance, step 44 in FIG. 5); and providing controls for repeating theprocessing of starting supply of a power to the detection unit and thenmeasuring the physical quantity based on a result of detection by thedetection unit and the processing for terminating supply of a power tothe detection unit, shifting its own state to the standby state, andreturning from the standby state after passage of the standby period(processing for shifting the operational state shown in FIG. 17).

Also in the program according to claim 4, the steps correspond to thesame embodiments as those in the information processing method accordingto claim 3 (Note that the program according to claim 4 is only anexample thereof).

The information processing apparatus according to claim 5 includes adetection unit (for instance, the sensor 3 in FIG. 1) for detecting aphysical quantity as a target for detection; a control unit (forinstance, the MCU 1 in FIG. 1) for measuring the physical quantity basedon a result of detection by the detection unit (for instance, samplingby the sampling section 24 in FIG. 3) and also controlling supply of apower to the detection unit (power control by the power control section21 in FIG. 3); and a storage unit (for instance, the timer section 22 inFIG. 3) for storing therein a period of time after measurement of thephysical quantity by the first control unit is finished untilmeasurement for the physical quantity is carried out next as a standbyperiod with the first control unit shifted to the standby state duringthe period. Therefore, the control unit starts supply of a power to thedetection to the detection unit, shifts its own state to the standbystate (for instance, the sleep state), then returns from the standbystate after passage of the standby period, and measures the physicalquantity based on a result of detection by the detection unit (forinstance, the information processing apparatus for shifting theoperating state in FIG. 2).

The information processing method according to claim 6 is executed by aninformation processing apparatus including a detection unit (forinstance, the sensor 3 in FIG. 1) for detecting a physical quantity as atarget for detection and a control unit (for instance, MCU 1 in FIG. 1)for measuring the physical quantity based on a result of detection bythe detection unit (for instance, sampling by the sampling section 24 inFIG. 3) and also controlling supply of a power to the detection unit(for instance, power control by the power control section 21 in FIG. 3),and the method includes the step (for instance, step 44 in FIG. 5) ofstoring a period of time after supply of a power to the detection unitis started by the control unit until a normal result of detection by thedetection unit is obtained as a standby period with the control unitshifted to the standby state (for instance, the sleep state) during theperiod; and the step (for instance, the processing for shifting theoperating state in FIG. 2) of providing controls for starting supply ofa power to the detection unit, shifting the control unit into thestandby state, returning the control unit from the standby state afterpassage of the standby period, and measuring the physical quantity basedon a result of detection by the detection unit.

Also in the program according to claim 7, the steps correspond to thesame embodiments as those in the information processing method accordingto claim 6 (Note that the program according to claim 7 is only anexample thereof).

The information processing apparatus according to claim 8 includes adetection unit (for instance, the sensor 3 in FIG. 1) for detecting aphysical quantity as a target for detection; a control unit (forinstance, the MCU 1 in FIG. 1) for measuring the physical quantity basedon a result of detection by the detection unit (for instance, samplingby the sampling section 24 in FIG. 10) and also controlling supply of apower to the detection unit (for instance, power control by the powercontrol unit 21 in FIG. 10); and an estimation unit (for instance, theestimation section 31 in FIG. 10) for estimating a normal result ofdetection by the detection unit obtained after passage of apredetermined period of time after supply of a power to the detectionunit is started based on a result of measurement of the physicalquantity by the control unit. Therefore, the control unit starts supplyof a power to the detection unit, measures the physical quantity basedon a result of detection by the detection unit, and stops, when a normalresult of detection is estimated by the estimation unit, supply of apower to the detection unit.

The information processing method according to claim 10 is executed byan information processing apparatus including a detection unit (thesensor 3 in FIG. 1) for detecting a physical quantity as a target fordetection and a control unit (for instance, the MCU 1 in FIG. 1) formeasuring the physical quantity based on a result of detection by thedetection unit (for instance, sampling with the sampling section 24 inFIG. 10) and also controlling supply of a power to the detection unit(for instance, power control by the power control section 21 in FIG.10), and the method includes the step of estimating a normal result ofdetection by the detection unit obtained after passage of apredetermined period of time after supply of a power to the detectionunit is started based on a result of measurement of the physicalquantity by the control unit (for instance, step S94 in FIG. 1); and thestep of providing controls for starting supply of a power to thedetection unit, measuring the physical quantity based on a result ofdetection by the detection unit, and stopping, when a normal result ofdetection is estimated by the estimation unit, supply of a power to thedetection unit (for instance, the processing for shifting the operatingstate shown in FIG. 8).

Also in the program according to claim 11, the steps correspond to thesame embodiments as those in the information processing method accordingto claim 10 (Note that the program according to claim 11 is only anexample thereof).

The information processing apparatus according to claim 12 includes aplurality of detection units (for instance, the GPS module 51 to the UVray sensor 57 in FIG. 12) each for detecting a physical quantity as atarget for detection; and a control unit (for instance, the MCU 1 inFIG. 12) for measuring the physical quantity based on a result ofdetection by one or more first detection units (for instance, theillumination sensor 56) among the plurality of detection units and alsocontrolling supply of a power to a second detection unit in response toa result of measurement of the physical quantity.

The second detection unit of the information processing apparatusaccording to claim 17 includes a first positioning unit for executingpositioning outdoors (for instance, the GPS module 51 in FIG. 12), and asecond positioning unit (for instance, the PHS module 52 in FIG. 12) forexecuting positioning indoors; and the control unit sets, when it isdetermined from a dose of ultraviolet rays measured based on a result ofdetection by the first detection unit that the control unit is presentoutdoors, higher priority to the first positioning unit as compared tothat to the second positioning unit, and controls supply of a power tothe first and second positioning units so that positioning is executedonly by the first positioning unit.

The first detection unit of the information processing apparatusaccording to claim 20 includes a first measuring unit (for instance, theillumination sensor 56 in FIG. 12) for measuring illumination intensityand a second measuring unit (for instance, the UV ray sensor 57 in FIG.12) for measuring a dose of ultraviolet rays; and the control unitcontrols supply of a power to the second measuring unit so thatmeasurement of a dose of ultraviolet rays is executed by the secondmeasuring unit when illumination intensity over the predeterminedthreshold value is measured by the first measuring unit.

The information processing apparatus according to claim 22 furtherincludes a storage unit (for instance, the timer section 22 in FIG. 3)for storing therein a period of time after supply of a power to thethird detection unit among the plurality of detection units is startedby the control unit until a normal result of detection by the detectionunit is obtained as a standby period with the control unit shifted tothe standby state (for instance, the sleep state) during the period.Therefore, the control unit starts supply of a power to the thirddetection unit, shifts its own state to the standby state, and returnsfrom the standby state after passage of the standby period, and measuresthe physical quantity based on a result of detection by the thirddetection unit.

The information processing apparatus according to claim 23 furtherincludes a storage unit (for instance, the buffer 93 in FIG. 19) forstoring therein data indicating the physical quantity measured by thecontrol unit. Therefore, the control unit supplies, when only apredetermined volume of data indicating the physical quantity isobtained by the storage unit, the predetermined volume of dataindicating the physical quantity to other control unit executing apredetermined processing (for instance, the Main MCU 81 in FIG. 19).

The information processing method according to claim 24 is executed byan information processing apparatus including a plurality of detectionunits each for detecting a physical quantity as a target for detection,and the method includes the step of providing controls (for instance,the processing for shifting the operating state in FIG. 13) formeasuring the physical quantity based on a result of detection by one ormore first detection units (for instance, the illumination sensor 56)among the plurality of detection units and also controlling supply of apower for a second detection unit according to a result of measurementof the physical quantity.

Also in the program according to claim 25, the steps correspond to thesame embodiments as those in the information processing method accordingto claim 24 (Note that the program according to claim 25 is only anexample thereof).

Embodiments of the present invention are described below with referenceto the related drawings.

FIG. 1 is a block diagram showing an example of configuration of aninformation processing apparatus in which the present invention isapplied. The information processing apparatus shown in FIG. 1 is, forinstance, a mobile telephone or a PDA (Personal Digital Assistant), or aportable device such as a compact personal computer (or a portionthereof).

The MCU (Micro Controller Unit) 1 is a one-chip micro computer whichdevelops, for instance, an application previously prepared on a RAM(Random Access Memory) inside thereof and controls operations of theentire information processing apparatus.

The MCU 1 shows ON/OFF (energized/not energized) of an FET (Field EffectTransistor) 2 according to a signal (sensor enable signal) outputtedfrom a GPO (General Purpose Output) terminal 11, and controls supply ofa power Vcc to a sensor 3. Further the MCU 1 executes sampling of asignal (a sensor output signal) inputted from the operating sensor 3with a power Vcc supplied thereto to a GPI (General Purpose Input)terminal 12 (measurement of a physical quantity).

The FET 2 supplies a power Vcc to the sensor 3 according to a signalinputted from the MCU 1.

The sensor 3 operates only while the power Vcc is being supplied via theFET 2, and outputs a signal indicating a result of detection to the GPIterminal 12 of the MCU 1. The sensor 3 is any of a temperature sensor, ahumidity sensor, an air pressure sensor, an illumination sensor, an UVray sensor, a gyro sensor, an acceleration sensor, and the like.

Further the sensor 3 may be any of a GPS (Global Positioning System)module, a PHS (Personal Handy Phone) module, a radio LAN (Local AreaNetwork) module based on the standard such as the IEEE (Institute ofElectrical and Electronics Engineers) 802.11a,b,g, or a communicationmodule such as Bluetooth (Registered trade mark), and display modulesuch as LCD (Liquid Crystal Display), and an image pick-up module suchas a CCD (Charge Coupled Device). That is, any module may be employed solong as the module operates with a certain cycle.

In the information processing apparatus having the configuration asdescribed above, to reduce the power consumption, controls are providedfor supply of a power Vcc to the sensor 3 and the operation state of theMCU 1 itself.

FIG. 2 is a view showing state transition of the MCU 1 as well as of thesensor 3.

As shown in FIG. 2, the operating state of the MCU 1 is divided to therun state and the sleep state, and the MCU 1 repeats the two operatingstates. That is, an intermittent operation is executed.

Herein the run state indicates the state in which a specified task isexecuted and controls, for instance, over supply of a power Vcc to thesensor 3.

The sleep state is the state in which power consumption is less thanthat in the run state. In the sleep state, when an interruption is madeaccording to the timing set in a timer during the run state, the runstate is restored.

The sleep state has the following different two meanings according to atype of OS (Operating System) executed by the MCU 1.

For instance, when the OS executed by the MCU 1 is a non-real time OS,the sleep state indicates a state in which a clock speed is lowered andexecution of programs excluding those of the minimum requiredinput/output management is stopped.

When an OS executed by the MCU 1 is a real time OS ensuring that, whenan event occurs, the event handler is activated within a predeterminedperiod of time, the sleep state indicates termination of a task beingexecuted. Therefore, in this case, restoration from the sleep stateindicates a processing for waking the task.

When the real time OS is used, as a result of interruption of a task,execution of another task is enabled, and if code instructing a taskwith the lowest priority to shift to the sleep state like in the case ofthe non-real time OS is described in the task, shift to the sleep stateis executed when there is no task to be executed.

Again in FIG. 2, the MCU 1 having started the state of Run MCU 1 at thetime point t₁ turns ON the FET 2 to start supply of a power Vcc to thesensor 3.

At this point of time, the sensor 3 is set in the pre power ON state,and starts output of a signal indicating a result of detection. In FIG.2, the time of point when the sensor 3 is set in the pre power ON stateis time point t₁, but to describe accurately, the time of point isslightly delayed from the time point t₁.

This “pre power ON state” is a state before the power On state in whicha normal result of detection can be outputted. In this state, the sensor3 can operate because the power Vcc is being supplied thereto, but thesensor 3 cannot normally output a result of detection.

Therefore, until the time point t₃ when the sensor 3 is enabled tonormally output a result of detection, the timer is set, and then thesensor shifts its own operating state to the state of Sleep #1. In FIG.2, the state of Sleep #2 is started at the time point t₂. In the stateof Sleep #1, a value for the GPO terminal 11 is preserved, and supply ofthe power Vcc to the sensor 3 is continued.

The MCU 1 returns to the state of Run #2 upon interruption by the timergenerated at the time point t₃, and executes sampling for an output fromthe sensor 3 for the first time. That is, sampling for an output fromthe sensor 3 in the pre power ON state is not executed. At the timepoint t₃ and on, the sensor 3 is in the power ON state, so that the MCU1 can obtain a normal value by sampling.

After sampling for an output from the sensor 3 is executed, the MCU 1turns OFF the FET 2 at the time point t₄, and stops supply of the powerVcc to the sensor 3. With this, the sensor 3 enters the power OFF statewith the operation stopped.

After the sensor 3 is turned OFF, the MCU 1 sets the timer, and sets itsown operating state again in the sleep state.

With this operation, the MCU 1 enters the state of Sleep #2 at the timepoint t₅, and preserves the state until the time point t₆ when aninterruption by the timer set in the state of Run #2 is generated. Atthe time point t₆ and on, state transition from the time point t₁ isagain repeated.

Some sensors cannot normally output a result of detection after supplyof the power Vcc is started until a predetermined period of time passes.If any of the sensors as described is used, the operating state of theMCU 1 is shifted to the sleep state and the state is maintained untilnormal output of detection is started. Thus, it is possible to reducepower consumption by the MCU 1 in proportion to the period of time inthe sleep state. Further it is possible to prevent an incorrect valuefrom being sampled and fetched.

Further as also the sensor 3 is deactivated immediately after a normalvalue is obtained by sampling (at the time point t₄ in FIG. 2), powerconsumption by the sensor 3 is reduced more as compared to the case inwhich the sensor 3 is kept activated until sampling is carried out next.

Further power consumption in the entire device is reduced, even when thedevice is operated for the same period of time, the informationprocessing apparatus can be run with a battery with a smaller capacityas a power supply for the device. This enables not only cost reduction,but also size reduction of the device body.

Operations of the MCU 1 for reducing power consumption are described indetail below with reference to a flow chart.

FIG. 3 is a block diagram showing an example of functional configurationof the MCU 1. At least a portion of the function block in FIG. 3 isrealized by execution of a specific program by the MCU 1.

A power control section 21 turns ON or OFF the FET 2 according to asignal outputted from the GPO terminal 11 under control by a statemanagement section 23.

A timer section 22 manages a timer and generates an interruption to thestate management section 23 at a time point set by the state managementsection 23. In response to this interruption, the state managementsection 23 restores the MCU 1 from the sleep state, and executes thesubsequent processing steps.

The state management section 23 manages state transition of the MCU 1.Further the state management section 23 executes the processing such assetting a time point when the run state is to be restored next while theMCU 1 is in the run state.

A sampling section 24 executes sampling for a signal (indicating aresult of detection by the sensor 3) inputted into the GPI terminal 12.The data obtained by sampling is outputted, for instance, to otherfunction block not shown and is used for a predetermined processtherein.

A sequence of operations in the MCU 1, FET 2, and sensor 3 shown in FIG.1 are described with reference to the sequence diagram shown in FIG. 4.

In step S1, the MCU 1 turns ON the FET 2 according to a signal outputtedfrom the GPO terminal 11 to start supply of a power Vcc to the sensor 3.

After supply of the power Vcc to the sensor 3 is started, in step S2,the MCU 1 sets a time point for returning to the run state, shifts tostep S3, and enters and stays in the sleep state until the set time isactivated (or until generation of an interruption). At this point oftime, for instance the state of Sleep #1 shown in FIG. 2 is started.

On the other hand, the FET 2 having received the signal outputted instep S1 from the MCU 1 energizes a section between a source and a drainin step S21 to start supply of the power Vcc to the sensor 3. The statein which the section between the source and drain has been energized ispreserved according to a signal sent from the MCU 1.

The sensor 3 starts running in step S31 in which supply of the power Vccto the sensor 3 is started (when the power is turned ON), and startsoutput of a result of detection to the MCU 1 in step S32. As the resultof detection outputted in this step is outputted in the pre power ONstate shown in FIG. 2 immediately after the operation of the sensor 3 isstarted, so that the result of detection is not normal. Sampling for aresult of detection is not performed in the MCU 1.

Output from the sensor 3 (output of a result of detection not beingnormal) is repeated with a predetermined cycle, and when output of anormal result of detection is enabled in step S33 (when the power ONstate is effected at the time point t₃ in FIG. 2), the MCU1 performssampling for the first time.

In step S4, the MCU 1 is restored from the sleep state in response toactivation of the timer having been set (for instance, to the state ofRun #2), shifts to step S5, and executes sampling for a result ofdetection outputted from the sensor 3.

After sampling for a normal result of detection sent from the sensor 3is finished, in step S6, the MCU 1 turns OFF the FET 2, and stops supplyof the power Vcc to the sensor 3.

The MCU 1 sets the timer in step S7, goes to step S8, and enters thesleep state again. With this operation, the MCU 1 is kept in the stateof, for instance, Sleep #2 shown in FIG. 2 until the timer is activated.

On the other hand, the FET 2 having received a signal from the MCU 1sets the source-drain section in the nonconductive state to stop supplyof the power Vcc to the sensor 3.

In step S34 where supply of the power Vcc to the sensor 3 is stopped,the sensor 3 stops the operation. The sensor 3 is thus preserved, forinstance, in the power OFF state shown in FIG. 2 until the power Vcc issupplied next time.

The processing by the MCU 1, FET 2, and sensor 3 is repeated, andintermittent operations by the MCU 1 and sensor 3 are realized, so thatpower consumption by the MCU 1 and sensor 3 is reduced.

Next operations of the MCU 1 are described with reference to the flowcharts shown in FIG. 5 and FIG. 6.

FIG. 5 is a flow chart showing the processing executed by the MCU 1 inthe run state.

The state management section 23 in the MCU 1 determines, in step S41,whether or not the flag under management thereby is clear. This flagindicates that the power for the sensor 3 is ON when the flag is set,and also that the power for the sensor 3 is OFF when the flag is clear.

When it is determined in step S41 that the flag is clear (the power forthe sensor 3 is OFF), the state management section 23 goes to step S42and turns ON the power for the sensor 3. In other words, the statemanagement section 23 controls the power control section 21 to turn ONthe FET 2 so that a signal is outputted from the GPO terminal 11.

In step S43, the state management section 23 sets the flag, goes to stepS44, and then sets the time point when an interruption is to begenerated. After the timer is set, the state management section 23 setsthe operating state of the MCU 1 in the sleep state in step S45. Whenthe interruption is generated, the processing shown in FIG. 6 isterminated, and when the state before the sleep state is effected isrestored, the processing in step S41 and on is repeated.

On the other hand, when it is determined in step S41 that the flag isnot clear (that the power to the sensor 3 is ON and the flag is set),the state management section 23 goes to step S46 to clear the flat. Forinstance, when the sampling (processing in step S63) is executed in theprocessing described hereinafter and shown in FIG. 6 is executed andthen the state management section 23 returns to the processing shown inFIG. 5, it is determined in step S41 that the flag is not clear.

In step S47, the state management section 23 sets the timer, goes tostep S45, and enters the sleep state.

Then the processing by the MCU 1 realized when the interruption handleris executed is described with reference to the flow chart shown in FIG.6.

When an interruption from the timer section 22 is generated in step S61,the state management section 23 activates the MCU 1 from the sleepstate, and determines in step S62 whether or not the flag is clear.

When it is determined in step S62 that the flag is not set, the statemanagement section 23 skips the processes in step S63 and step S64described hereinafter, and is activated in step S65. With thisoperation, the processing shown in FIG. 5 is started.

On the other hand, when it is determined in step S62 that the flag isset, the state management section 23 goes to step S63 and makes asampling section 24 sample a result of detection by the sensor 3. Theinterruption in step S61 is set so that the interruption is generated atthe time point when the sensor 3 starts outputting a normal result ofdetection, and therefore a normal value is acquired by the sampling inthis step.

In step S64, the state management section 23 controls the power controlsection 21 to output a signal for turning OFF the FET 2 for stoppingsupply of the power Vcc to the sensor 3. Then the state managementsection 23 goes to step S65, and restores the operating state of the MCU1 from the state for execution of the interruption handler.

Descriptions above assume the case where supply of the power Vcc to thesensor 3 is continued until output of a normal result of detection isstarted, but in some cases, a value for a normal result of detection isestimated from an abnormal result of detection outputted before outputof a normal result of detection is started.

In this case, therefore, an output from the sensor 3 indicating anabnormal result of detection is sampled a predetermined number of times,and when a value for a normal result of detection can be estimated basedon a result of this sampling, the supply of the power Vcc to the sensor3 may be stopped even before output of a normal result of detection isstarted.

With this configuration, a period of time for supply of the power Vcc tothe sensor 3 can be made shorter as compared to a case in which supplyof the power Vcc is continued until output of a normal result ofdetection is actually started. That is, power consumption by the sensor3 can be reduced.

FIG. 7 is a view showing transition of a humidity outputted from ahumidity sensor.

A horizontal axis in FIG. 7 indicates time (second), while the verticalaxis indicates humidity (%). In the example shown in FIG. 7, a value isoutputted (measured) once for every second.

After measurement (power supply) is started, a humidity of around 50% isoutputted for a period from 1 second to 4 seconds after start of powersupply, and then values providing a curve when the values are connectedwith lines are outputted after the initial period described above until8 seconds after start of power supply. In 8 seconds after start of powersupply and on, a substantially constant value is outputted.

Assuming herein that the humidity value of around 95% at 8 seconds afterstart of measurement is a normal value, a normal value outputted in 8seconds after start of measurement can be estimated from results ofsampling performed in 5 seconds, 6 seconds, and 7 seconds after start ofpower supply as well as the performance of this humidity sensor. Forinstance, when sampling performed in 7 seconds after start ofmeasurement is finished, supply of the power Vcc to the humidity sensoris stopped.

With this configuration, as compared to the case in which power supplyis continued until 8 seconds after start of measurement, powerconsumption by the humidity sensor can be reduced by a ratecorresponding to 1 second.

It is needless to say that the power control as described above can beapplied to any type of sensor such as a temperature sensor other thanthe humidity sensor as described above on the condition that the sensorcan output an estimated value for a normal result of detection based ona result of sampling performed before output of a normal result ofdetection is started.

FIG. 8 is a view showing state transition of the MCU 1 as well as of thesensor 3 (a sensor having the output performance enabling estimation ofa value for a normal result of detection from a result of samplingperformed before output of a normal result of detection is started).

As shown in FIG. 8, the MCU 1 executes intermittent operations andchanges the operating state from Run #1, Sleep #1, Run #2, Sleep #2, Run#3, Sleep #3 . . . .

In the state of Run #1 effected at the time point t₁₁, the MCU 1 turnsON the power for the sensor 3 and sets a timer, and then changes theoperating state of its own to the state of Sleep #1 at the time pointt12. In response to control by the MCU 1, also the sensor 3 is turned ONat the time point t₁₁.

In the state of Run #2 effected in response to an interruption generatedat the time point t₁₃, the MCU 1 executes sampling for an output fromthe sensor 3 and sets the timer, and then at the time point t₁₄, the MCU1 changes the operating state of its own to the state of Sleep #2. Thevalue obtained by sampling performed in the state of Run #2 does notindicate a normal value yet. A result of sampling expressed by a valuethat is not normal is temporally stored in a buffer.

In the state of Run #3 effected in response to an interruption generatedat the time point t₁₅, the MCU 1 executes sampling for an output fromthe sensor 3, and estimates a value for a normal result of detectionbased on the obtained result of sampling as well as on the samplingresult stored in the buffer and the performance of the sensor 3. Thatis, in the example shown in FIG. 8, a value of a normal result ofdetection is estimated from the result of sampling executed twice,namely in the state of Run #2 and in the state of Run #3.

When estimation of a normal result of detection is finished, the MCI 1turns OFF power for the sensor 3, sets a timer, and changes theoperating state of its own to the state of Sleep #3. In response tocontrol by the CMU 1, also the sensor 3 is deactivated at the time pointt₁₆ (the power turned OFF).

FIG. 9 is a view showing the effect provided when the operational statesof the MCU 1 and sensor 3 are shifted as shown in FIG. 8.

In FIG. 9, the upper row shows transition of the operational state ofthe sensor 3 shown in FIG. 2, while the lower row shows transition ofthe operational state of the sensor 3 shown in FIG. 8. The time plottedalong the horizontal axis in FIG. 9 is based on the time shown in FIG.2.

As shown in the upper row in FIG. 9, when the operational state shiftsas shown in FIG. 2, the power Vcc is supplied to the sensor 3 from thetime point t₁ until the time point t₄, but when the operational stateshifts as shown in FIG. 8, supply of the power Vcc to the sensor 3 iscontinued from the time point t₁ until the time point t₁₆ (See FIG. 8)before time point t₄.

That is, the time for supply of the power Vcc to the sensor 3 isshortened by a rate corresponding to a period of time from time pointt₁₆ to time point t₄. In FIG. 9, the period of time from time point t₁to time point t₆ corresponds to the period of time from time point t₁₁to time point t₁₈, while the period of time from time point t₁ to timepoint t₁₆ corresponds to the period of time from time point t₁₁ to timepoint t₁₆ shown in FIG. 8.

In the case as shown in FIG. 8, where the a value for a normal result ofdetection is estimated from a result of sampling performed up to thepoint of time and supply of the power Vcc to the sensor 3 is stoppedaccording to the value, power consumption by the sensor 3 can bereduced, but the MCU 1 is activated more (and a period of running timethereof becomes longer) as compared to the case in which the sleep stateis preserved until the sensor 3 starts outputting a normal value asshown in FIG. 2.

Therefore, the state transition shown in FIG. 8 may be allowable onlywhen a quantity of consumed power reduced by shortening the period ofsupply of the power Vcc to the sensor 3 is larger than a quantity ofconsumed power increased by prolonging the run state of the MCU 1 asexpressed by the following equation:(a−b)*c>=d*ewherein “a” indicates a total quantity of consumed power in the runstate of the MCU 1 in the case where the state transition shown in FIG.2 is employed. That is, “a” indicates a value obtained by multiplyingthe time obtained by adding the time (t₂−t₁) for the Run #1 to the time(t₅−t₃) for the Run #2 state in FIG. 2 by the power consumption by theMCU 1 in the run state.

In the equation above, “b” indicates a total quantity of consumed powerby the MCU 1 in the sleep state in the case where the state transitionin FIG. 2 is employed. That is, “b” indicates a value by multiplying thetime obtained by adding the time (t₃−t₂) for the Sleep #1 to the time(t₆-t₅) for the Sleep #2 state in FIG. 2 by the power consumption by theMCU 1 in the sleep state.

In the equation above, “c” indicates a prolonged period of time for therun state of the MCU 1 when the state transition shown in FIG. 8 isemployed as compared to that when the state transition shown in FIG. 2is employed. That is, “c” indicates a value obtained by subtracting thetime (t₂−t₁) for the Run #1 and time (t₅−t₃) for the Run #2 state inFIG. 2 from a sum of the time (t₁₂−t₁₁) for the Run #1, the time(t₁₄−t₁₃) for the Run #2 state, and the time the (t₁₇−t₁₅) for the Run#3 state in FIG. 8.

In the equation above, “d” indicates consumed power by the sensor 3.

In the equation above, “e” indicates the time for supply of the powerVcc to the sensor 3 shortened by employing the state transition shown inFIG. 8 as compared to that shown in FIG. 2. That is, “e” indicates theperiod of time from time point t₁₆ to time point t₄ in FIG. 9.

Only when the relation as described above is satisfied, total powerconsumption in the entire device can be reduced without fail byemploying the state transition in FIG. 8 for the MCU 1 and sensor 3.Further a value for a normal result of detection can be obtained byestimation.

FIG. 10 is another block diagram showing an example of functionalconfiguration of the MCU 1. The same reference numerals are assigned tothe same components as those in FIG. 3. Description concerning thecomponents already described above is omitted.

The estimation section 31 fetches a result of sampling for an outputfrom the sensor 3 supplied from the sampling section 24 and stores thedata in a buffer not shown. For instance, when a plurality of samplingresults are acquired, the estimation section 31 estimates a value for anormal result of detection based on the acquired sampling results and onperformance of the sensor 3. When a value for a normal result ofdetection can be estimated, the estimation section 31 outputs a signalindicating that estimation of a normal result of detection is possibleto the power control section 21.

For instance, when a value for a normal result of detection is estimatedbased on a result of sampling executed twice, an estimated value y canbe obtained through the following equation:y=(y ₂ −y ₁)/(t ₂ −t ₁)*t ₃ +dwherein t₁ and t₂ (t₂>t₁) indicates the time points for first samplingand second sampling respectively; y₁ and y₂ (y₂>y₁) indicates valuesobtained in the first sampling and in the second sampling respectively;y indicates a value (estimated value) for a normal result of detection;t₃ indicates the time required until a normal result of detection isoutputted; and d indicates an offset.

Similarly, an algorithm for estimation is decided according toperformance of the sensor 3 and is installed in the estimation section31.

When the estimation section 31 can estimate a value for a normal resultof detection based on a result of first sampling and the performance ofthe sensor 3, it is not necessary for the sampling section 24 to performsampling several times. In this case, when sampling is carried out once,supply of the power Vcc to the sensor 3 is stopped, and an operationalstate of the MCU 1 is shifted to the sleep state.

Next, the processing of the MCU 1 for controlling supply of the powerVcc to the sensor 3 following the state transition shown in FIG. 8 isdescribed with reference to the flow chart in FIG. 11.

In step S81, the state management section 23 (in FIG. 10) in the MCU 1controls the power control section 21 to start supply of the power Vccto the sensor 3.

In step S82, the state management section 23 sets a time point forinterruption, and in step S83, changes the operating state of the MCU 1to the sleep state. With this operation, the operating state of MCU 1changes, for instance, to the state of Sleep #1 via the state of Run #1shown in FIG. 8.

When an interruption is generated and the MCU 1 returns the stateeffected just before the sleep state was effected, in step S84, thesampling section 24 executes sampling for an output from the sensor 3under controls by the state management section 23. A result of samplingby the sampling section 24 is outputted to the estimation section 31.

In step S85, the estimation section 31 fetches a result of samplingsupplied from the sampling section 24, and stores the data in a buffernot shown.

In step S86, the state management section 23 sets a time point forinterruption, goes to step S87, and shifts the operating state of theMCU 1 to the sleep state. With this operation, the operating state ofthe MCU 1 is changed, for instance, to the state of Sleep #2 via thestate of Run #2 shown in FIG. 8.

The process steps from step S88 to step S91 are the same as those fromstep S84 to step S87. In step S88, the sampling section 24 performssampling for an output from the sensor 3 with the system control shiftedto step S89, and then a result of the sampling is stored by theestimation section 31 in the buffer. Further in step S90, a timer isset. In step S91, the operating state of the MCU 1 is shifted to thesleep state.

The process steps from S88 to S91 are repeated until sampling resultsenabling estimation of a normal result of detection including a resultof sampling in step S92 are obtained.

In step S92, the sampling section 24 executes sampling for an outputfrom the sensor 3 under control by the state management section 23, andsupplies a result of the sampling to the estimation section 31.

The estimation section 31 stores, in step S93, a result of sampling bythe sampling section 24 in a buffer.

In step S94, the estimation section 31 estimates value for a normalresult of detection from the sampling result stored in the buffer andthe performance of the sensor 3, and, when the estimation can be made,outputs a signal indicating the possibility of estimation to the powercontrol section 21.

The power control section 21 outputs, in step S95, a signal for turningOFF the FET 2 from the GPO terminal 11 to stop supply of the power Vccto the sensor 3.

In step S96, the state management section 23 sets a timer, goes to stepS97, and shifts the operating state of the MCU 1 to the sleep state.With this operation, the operating state of the MCU 1 is changed, forinstance, via the state of Run #3 shown in FIG. 8, to the state of Sleep#3. Then an interruption is generated, and when the processing forexecuting the interruption handler as shown in FIG. 6 is finished, theprocess steps in step S81 and on as shown in FIG. 11 are repeated.

With the processing as described above, a period of time required forsupply of the power Vcc to the sensor 3 can further be shortened.

FIG. 12 is a block diagram showing another example of configuration ofthe information processing apparatus in which the present invention isapplied.

Connected to the MCU 1 shown in FIG. 12 are a GPS module 51 and a PHSmodule 52 each as a sensor for detecting a position of the informationprocessing apparatus, a gyro (gyro compass) 53 for detecting adirection, an acceleration sensor 54 for detecting an acceleration, ahumidity sensor 55 for detecting a humidity, an illumination sensor 56for detecting an illumination, and a UV ray sensor 57 for detecting adose of UV ray. When it is not necessary to discretely describe each ofthe GPS modules 51 through the UV ray sensor 57, a generic word ofsensor is used.

An FET not shown for controlling supply of the power Vcc to each sensoris connected to each of the GPS modules 51 through the UV ray sensor 57.When the MCU 1 turns this FET ON or OFF, supply of the power Vcc to eachsensor is controlled.

The MCU 1 shown in FIG. 12 is basically the same as that shown inFIG. 1. The MCU 1 shown in FIG. 12 turns ON or OFF the FET connected toeach sensor, and fetches a result of detection from a signal outputtedfrom each sensor and inputted into the GPI terminal.

In the information processing apparatus with the configuration asdescribed above, the situation in which the information processingapparatus is placed is detected by the MCU 1 based on an output from atleast one of the GPS modules 51 through the UV ray sensor 57, and supplyof the power Vcc to other sensors not or little required to run in thedetected situation (sensors each with low sensor) is stopped.

For instance, a sensor much consuming a power is regarded as a sensorwith a lower priority, and supply of the power Vcc to the sensor isstopped.

With this feature, although the power Vcc is supplied for a relativelylong period of time to sensors consuming a power a little for detectingthe situation, the power is supplied to sensors much consuming a poweronly when the sensors are to be run, and as a result power consumptionin the entire device can be reduced.

FIG. 13 is a view showing an example of state transition in a case wherethe situation is detected based on outputs from the gyro 53 and theacceleration sensor 54, and supply of the power Vcc to the GPS module 51more consuming a power as compared to the gyro 53 and the accelerationsensor 54 is stopped.

In the example shown in FIG. 13, the power Vcc is supplied to the gyro53 and the acceleration sensor 54 used for detecting the situation bothin the run state and in the sleep state of the MCU 1. Therefore, whenthe gyro 53 and acceleration sensor 54 are ON, signals indicatingdirections and accelerations of the components are supplied to the MCU1.

The MCU 1 supplies the power Vcc to the GPS module 51, based on thedirections and accelerations sampled in the run state, only when it isdetermined that a user carrying the information processing apparatus ismoving with a certain velocity.

The situation detected in this step indicates whether or not theinformation processing apparatus is moving with a certain velocity.

When the user carrying the information processing apparatus is notmoving, also the position detected by the GPS module 51 does not change,so that operations of the sensors are not required. As described above,supply of the power Vcc to the GPS module 51 is controlled. Powerconsumption by the GPS module 51 can be reduced more as compared to thecase where the power Vcc is supplied to the GPS module 51 even when thenecessity of running the module is rather low.

In the state of Run #1 started at the time point t21, the MCU 1 performssampling for outputs from the gyro 53 and the acceleration sensor 54,and computes a moving speed of the user carrying the informationprocessing apparatus. Further based on a result of the operation, whenit is determined that the user's moving speed is less than the thresholdvalue, the MPU 1 stops supply of the power Vcc to the GPS module 51.

In response to this operation, the GPS module 51 having been active isdeactivated, for instance, at the time point t₂₂.

The MCU 1 stops supply of the power Vcc to the GPS module 51, sets atimer, and shifts the operating state of its own to the state of Sleep#1 at the time point t₂₃.

The MCU 1 restored from the sleep state upon an interruption generatedat the time point t₂₄ computes a moving speed of the user carrying theinformation processing apparatus, in the state of Run #2, based on thesampling results for outputs from the gyro 53 and acceleration sensor 54like in the state of Run #1.

For instance, when it is determined based on a result of computing thatthe user is moving at a speed higher than the threshold value, the MCU 1starts supply of the power Vcc to the GPS module 51.

In response to this operation, the GPS module 51 having been in thepower OFF state resumes the operation, for instance, at the time pointt₂₅.

The MCU 1 starts supply of the power Vcc to the GPS module 51 andperforms measurement of a position or the like based on a signaloutputted from the GPS module 51, sets a timer according to thenecessity, and shifts the operating state of its own to the sleep state.

A power consumption rate in the gyro 53 and in the acceleration sensor54 is about 1.2 mW respectively (totally about 2.4 mW), while that inthe GPS module 51 is about 413 mW. Therefore, when the state transitionas shown in FIG. 13 is realized, an operating time of sensors eachconsuming a power 150 times or more is to be short. Thus, powerconsumption in the entire device can be reduced.

FIG. 14 is a block diagram showing an example of functionalconfiguration of the MCU 1 shown in FIG. 12. The same reference numeralsare assigned to the same components as those shown in FIG. 3 and FIG.10. Descriptions of the duplicated components are omitted herefrom.

The power control section 21 turns ON or OFF an FET connected to each ofthe GSP module 51 through the UV ray sensor 57, and controls supply ofthe power Vcc to the sensor.

The sampling section 24 executes sampling for outputs from active onesamong the GSP module 51 through the UV ray sensor 57, and outputs aresult of sampling to a situation detecting section 71 according to thenecessity.

The situation detecting section 71 detects a situation under which theinformation processing apparatus is placed (such as a moving speedthereof) based on sampling results outputted from, for instance, thegyro 53 and acceleration sensor 54 and supplied from the samplingsection 24. The situation detecting section 71 makes the power controlsection 21 control supply of the power Vcc to each sensor according tothe detected situation.

The processing performed by the MCU 1 to detect a situation based onoutputs from the gyro 53 and acceleration sensor 54 and control supplyof the power Vcc to the GPS module 51, the priority of which is lower inthe detected situation, is described below with reference to the flowchart in FIG. 15.

In step S111, the sampling section 24 of the MCU 1 (Refer to FIG. 14)carries out sampling for outputs from the gyro 53 and accelerationsensor 54, and outputs the sampling result to the situation detectingsection 71.

In step S112, the situation detecting section 71 computes a moving speed(velocity and direction) of the information processing apparatus basedon a result of sampling supplied from the sampling section 24, then goesto step S113, and determines whether or not the information processingapparatus little moves, namely whether or not the computed moving speedis less than a predetermined threshold value.

When it is determined in step S113 that the information processingapparatus moves little, the situation detecting section 71 outputs asignal indicating the situation to the power control section 21, andgoes to step S114.

In step S114, the power control section 21 stops supply of the power Vccto the GPS module 51 as a sensor to be controlled. Then the processsteps in step S116 and on are executed. With the operations describedabove, the GPS module 51 regarded as a sensor with lower priority in thesituation where the information processing apparatus little moves isstopped.

On the other hand, when it is determined in step S113 that theinformation processing apparatus is moving with a speed higher than thethreshold value, the situation detecting section 71 outputs a signalindicating the situation to the state management section 23, and goes tostep S115.

The state management section 23 determines in step S115 whether or notthe flag is clear, and when it is determined that the flag is not clear(the power for the GPS module 51 is ON and the flag is set), the statemanagement section 23 goes to step S116.

In step S116, the state management section 23 clears the flag, goes tostep S117, and sets a timer.

After the timer is set, the state management section 23 goes to stepS118, and shifts the operating state of the MCU 1 to the sleep state.After an interruption is generated and the processing for executing theinterruption handler as shown in FIG. 6 is carried out, the processsteps in step S111 and on are repeated.

When the state management section 23 determines in step S115 that theflag is clear (the power for the GPS module 51 is OFF), the statemanagement section 23 goes to step S119, and controls the power controlsection 21 to start supply of the power Vcc to the GPS module 51.

When the information processing apparatus is moving at a speed higherthan the threshold value and also the power Vcc is not supplied to theGPS module 51, supply of the power Vcc is started. In the situation whenthe information processing apparatus is moving at a certain speed, theGPS module 51 is regarded as a sensor with high priority.

In step S120, the state management section 23 sets the flag, goes tostep S121, and sets a timer. After the timer is set, the statemanagement section 23 goes to step S118, and the state managementsection 23 changes the operating state of its own to the sleep state.

With the processing as described above, only when the informationprocessing apparatus is moving at a speed not less than the thresholdvalue, the power Vcc is supplied to the GPS module 51.

Assuming, for instance, that the precision in measurement of a positionby the GPS module 51 is 20 m. When a travel of the informationprocessing apparatus within a cycle of positioning (a value obtained bymultiplying a velocity computed based on outputs from the gyro 53 andacceleration sensor 54 by a cycle in positioning by the GPS module 51)is not more than 20 m, the power Vcc is not supplied to the GPS module51. When the value is over 20 m, supply of the power Vcc to the GPSmodule 51 is started.

That is, not only the sensors to be activated, but also the samplingcycle changes according to the situation under which the informationprocessing apparatus is placed currently. For instance, when a usercarrying the information processing apparatus is moving by car, thesampling for an output from the GPS module 51 (positioning) is performedwith a shorter cycle as compared to that when the user is moving onfoot.

As described above, a cycle of sampling for an output from a sensor ischanged according to the current situation. Power consumption by the MCU1 can be reduced.

In the case described above, the current situation is detected based onoutputs from the gyro 53 and acceleration sensor 54, and supply of thepower Vcc to the GPS module 51 is controlled according to the detectedsituation, but also the configuration is allowable in which the currentsituation is detected based on outputs from other sensors and supply ofthe power Vcc to sensors other than the other sensors is controlledaccording to the detected situation.

For instance, the configuration is allowable in which whether or not aninformation processing apparatus is inside a house is determinedaccording to outputs from the illumination sensor 56 and the UV raysensor 57. The power Vcc is supplied to the GPS module 51 only when itis determined that the information processing apparatus is outside thehouse.

When the information processing apparatus is inside a house, sometimesthe GPS module 51 cannot accurately position the information processingapparatus. Thus, power consumption in the information processingapparatus as a whole can be reduced by stopping supply of the power Vccto the GPS module 51. In this case, the illumination sensor 56 and theUV ray sensor 57 still run, but the power consumption is substantiallylower than that by the GPS module 51.

Next, description is made with reference to the flow chart shown in FIG.16 for a case in which the current situation is detected based onoutputs from the illumination sensor 56 and UV ray sensor 57 and supplyof the power Vcc to the GPS module 51 is controlled by the MCU 1 basedon outputs from the illumination sensor 56 and the UV ray sensor 57.

In step S131, the sampling section 24 of the MCU 1 carries out samplingfor an output from the illumination sensor 56, and outputs the samplingresult to the situation detecting section 71.

In step S132, the situation detecting section 71 computes theillumination based on the sampling result supplied from the samplingsection 24, goes to step S133, and determines whether or not it isbright or dark, namely whether the computed illumination is higher thanthe predetermined threshold value.

In step S133, when the situation detecting section 71 determines thatthe information processing apparatus is in a place having illuminationnot higher than the predetermined threshold value, the situationdetecting section 71 outputs a signal indicating the situation to thepower control section 21, and goes to step S134.

In step S134, when the power Vcc is supplied to the UV ray sensor 57,the power control section 21 stops the supply.

When relatively low illumination is detected, it is highly likely thatthe information processing apparatus is inside a house, so that, in manycases, the detection of a dose of UV ray is not absolutely necessary.Thus, under the circumstances as described above, priority of the UV raysensor 57 becomes low, and power consumption can be reduced by stoppingan operation of the UV ray sensor 57.

The process step then returns to the step S131, and the process steps instep S131 and on are repeated.

On the other hand, in step S133, when the situation detecting section 71determines that the information processing apparatus is in a placehaving illumination not lower than the predetermined threshold value,the situation detecting section 71 outputs a signal indicating thesituation to the power control section 21, and goes to step S135.

In step S135, the power control section 21 starts, when the power Vcc isnot supplied to the UV ray sensor 57, the supply. From the UV ray sensor57 is supplied a signal indicating a detected dose of UV ray.

In step S136, the sampling section 24 executes sampling of an outputfrom the UV ray sensor 57, and outputs a sampling result to thesituation detecting section 71.

In step S137, the situation detecting section 71 computes a dose of UVray based on the sampling result supplied from the sampling section 24,goes to step S138, and determines whether or not the dose of UV ray ishigher than the predetermined threshold value.

In step S138, when the situation detecting section 71 determines that adose of UV ray is higher than the predetermined threshold value, thesituation detecting section 71 recognizes that it is highly likely thatthe information processing apparatus is carried to the outdoors, andoutputs a signal indicating the situation to the power control section21.

In step S139, the power control section 21 starts, in response to asignal supplied from the situation detecting section 71, an intermittentoperation of the GPS module 51, and executes positioning. When it ishighly likely that the information processing apparatus is carried tothe outdoors, the GPS module 51 becomes a sensor having a high priority,and operations thereof are started.

As described hereinafter, positioning by the GPS module 51 in this stepcan be designed to be executed while the power consumption thereof isreduced. Intermittent operations by the GPS module 51 are describedhereinafter with reference to FIG. 17.

The process step returns to the step S131 after the intermittentoperations by the GPS module 51 are started, and the process steps instep S131 and on are repeated.

On the other hand, in step S138, when the situation detecting section 71determines that a dose of UV ray is lower than the predeterminedthreshold value, the situation detecting section 71 recognizes that itis highly likely that the information processing apparatus is inside ahouse, and outputs a signal indicating the situation to the powercontrol section 21.

In step S140, when the power Vcc is supplied to the GPS module 51, thepower control section 21 stops the supply, and repeats the process stepsin step S131 and on.

In a case where it is detected that the information processing apparatusis inside a house, a PHS module 52, which is also used as a positioningdevice but is mutually exclusive with the GPS module 51, may be operatedto execute positioning. The PHS module 52 is a sensor capable ofpositioning even when the information processing apparatus is inside ahouse. Positioning can be performed under any circumstances with theconfiguration in which the GPS module 51 executes positioning when theinformation processing apparatus is outside a house, while the PHSmodule 52 executes positioning when the information processing apparatusis inside a house.

FIG. 17 is a view showing an example of intermittent operations of theGPS module 51 executed in step S139 shown in FIG. 16.

The MCU 1 makes at the time point time₃₁ a cold start with which acurrent positioning is started without employing a result of theprevious positioning, and shifts to the sleep state at the time pointtime₃₂ just when the MCU 1 detects that outputs from the GPS module 51contain a positioning bit. This positioning bit is outputted when theGPS module 51 captures a satellite.

In FIG. 17, when the period of time during which a satellite is notcaptured continues for about 15 minutes, the situation is assumed as atime out (termination of search for a satellite).

Further, before shifted to the sleep state, the MCU 1 not only sets atimer, but also stops supply of the power Vcc to the GPS module 51 andstores information on a satellite captured by the GPS module 51. The GPSmodule 51 enters the state of Power Off in response to controls by theMCU 1.

In a case where a satellite has been captured once, and informationthereof is stored, the MCU 1 can make, at the start of the nextpositioning, a warm start or a hot start with which positioning isstarted based on the stored information on the satellite or the like.Therefore the MCU 1 makes the GPS module 51 execute an intermittentoperation in a cycle in which the capture is started before a certainperiod of time ready for making a warm start or a hot start passes.

In the example in FIG. 17, it is assumed that the GPS module 51 executesan intermittent operation in a five-minute cycle. The five minutesrepresents a period of time during which a warm start or a hot start canbe made.

In a case of a warm start or a hot start, positioning can be performedat an earlier timing as compared to that of a cold start, and the MCU 1returns by an interruption generated at the time point t₃₃, which is 5minutes after the MCU 1 enters the sleep state, and makes instructionsto supply the power Vcc to the GPS module 51. Further, the MCU 1executes positioning based on an output from the GPS module 51 between,for instance, 1 second and 2 seconds.

After completing the positioning, the MCU 1 sets a timer, stops supplyof the power Vcc to the GPS module 51, and then enters the sleep stateonly for a period of time during which a warm start or a hot start canbe made. The GPS module 51 also enters the state of Power Off inresponse to the controls by the MCU 1.

Operations as described above are repeated and the MCU 1 and GPS module51 execute intermittent operations from the time point t₃₅ to t₃₆ andthe time point t₃₇ to t₃₈. At the time point t₃₉, operations similar tothose at the time point t₃₃ and on are repeated.

With the state transition as described above, time required foroperations of the MCU 1 and GPS module 51 can be shortened, and MCU 1returns from the sleep state before a period of time ready for making awarm start or a hot start passes, so that a quick positioning after thereturn is also possible.

Next, other processing of the MCU 1 for detecting the situation in whichthe information processing apparatus is put, and for controlling supplyof the power Vcc to other sensors based on a result of detection isdescribed with reference to the flow chart in FIG. 18.

In the processing shown in FIG. 18, as is the case with that shown inFIG. 16, the situation is detected based on not only an output from anillumination sensor 56 and a UV ray sensor 57 but also an output from ahumidity sensor 55.

When humidity changes significantly, it is highly likely that a usercarrying an information processing apparatus moves from inside a room tothe outside, from outside a room to the inside, from inside a room toinside another room, or the like.

Thus, when a significant change in humidity as described above isdetected, whether or not positioning by the GPS module 51 is possible isconfirmed once, so that a problem such that the positioning is notperformed even though it is possible can be prevented.

In step S151, the sampling section 24 in FIG. 14 is activated by a timerin a certain cycle, executes sampling for an output from the humiditysensor 55, and outputs the sampling result to the situation detectingsection 71.

In step S152, the situation detecting section 71 computes the humiditybased on the sampling result supplied from the sampling section 24, goesto step S153, and determines whether or not the humidity changes moresignificantly than a predetermined threshold value width, for instance,as compared to that sampled last time.

In step S153, when the situation detecting section 71 determines thatthe humidity changes significantly, the situation detecting section 71outputs a signal indicating the situation to the power control section21, and goes to step S154.

In step S154, when the power Vcc is not supplied to the GPS module 51,the power control section 21 starts the supply. When a significantchange in humidity is detected, the GPS module 51 becomes a sensorhaving a high priority.

The sampling section 24 executes sampling based on an output from theGPS module 51. Then the process step goes to step S163 describedhereinafter.

On the other hand, in step S153, when the situation detecting section 71determines that the humidity does not change significantly, thesituation detecting section 71 outputs a signal indicating the situationto the power control section 21, and goes to step S155.

In step S155, the sampling section 24 carries out sampling for an outputfrom the illumination sensor 56, and outputs the sampling result to thesituation detecting section 71.

In step S156, the situation detecting section 71 computes theillumination based on the sampling result supplied from the samplingsection 24, goes to step S157, and determines whether it is bright ordark, namely whether or not the computed illumination is higher than thepredetermined threshold value. In step S157, when it is not determinedthat the computed illumination is higher than the predeterminedthreshold value, the process step goes to step S163.

In step S157, when the situation detecting section 71 determines thatthe information processing apparatus is in a place having illuminationhigher than the predetermined threshold value, the situation detectingsection 71 outputs a signal indicating the situation to the powercontrol section 21, and goes to step S158.

In step S158, the power control section 21 starts, when the power Vcc isnot supplied to the UV ray sensor 57, the supply. From the UV ray sensor57 is thereby supplied a signal indicating a detected dose of UV ray tothe MCU 1.

In step S159, the sampling section 24 executes sampling for an outputfrom the UV ray sensor 57, and outputs the sampling result to thesituation detecting section 71.

In step S160, the situation detecting section 71 computes a dose of UVray based on the sampling result supplied from the sampling section 24,goes to step S161 when the calculation is finished, and makes the powercontrol section 21 stop the supply of the power Vcc to the UV ray sensor57.

In step S162, the situation detecting section 71 determines whether ornot a dose of UV ray is higher than the predetermined threshold value.When the situation detecting section 71 determines that the dose of UVray is higher than the predetermined threshold value, the situationdetecting section 71 recognizes that it is highly likely that theinformation processing apparatus is in the outdoor, and outputs a signalindicating the situation to the power control section 21.

In addition to a case where it is determined in step S162 that a dose ofUV ray is higher than the predetermined threshold value, in a case wherepositioning is executed in step S154 and in a case where it is notdetermined in step S159 that the information processing apparatus is ina place having illumination higher than the predetermined thresholdvalue, the power control section 21 starts in step S1163 an intermittentoperation (for instance, an operation in FIG. 17) of the GPS module 51.

Then the state management section 23 sets a timer or the like, entersthe sleep state in step S1164, and repeats the process steps in stepS151 and on.

On the other hand, in step S162, when it is determined that a dose of UVray is lower than the predetermined threshold value, the situationdetecting section 71 recognizes that it is highly likely that theinformation processing apparatus is inside a house, and outputs a signalindicating the situation to the power control section 21.

In step S165, when the power Vcc is supplied to the GPS module 51, thepower control section 21 stops the supply, goes to step S164 and entersthe sleep state.

After the process steps described above, when a relatively significantchange in humidity is detected, positioning by the GPS module 51 iscarried out once, and after the positioning, another positioning by anintermittent operation as described with reference to FIG. 17 isperformed. With this configuration, positioning by the GPS module 51 isensured even in a case where the situation changes (in a case where theinformation processing apparatus is moved), while power consumption isreduced.

In an intermittent operation as shown in FIG. 17, once the power controlsection 21 enters the sleep state, the next positioning is not carriedout, for instance, in 5 minutes. However, when it is detected that theinformation processing apparatus is moved, positioning is executed once,so that a problem such that the positioning is not performed even thougha user carrying the information processing apparatus moves can beprevented.

Movement of a user carrying the information processing apparatus can bedetected based on an output from the gyro 53 or the acceleration sensor54 as described above, however, the humidity sensor 55 generallyconsumes less power than the gyro 53 or the acceleration sensor 54 (Apower consumption rate in the gyro 53 and in the acceleration sensor 54is both about 1.2 mW, while that in the humidity sensor 55 is about 0.7mW).

Thus the configuration is allowable in which, even when the samephysical quantity is to be detected, the MCU 1 sets a priority ofsensors, and selects one to be operated, so that the sensor consumingpower as little as possible is used.

In the configuration described above, the MCU 1 is intermittently movedalong with, for instance, a sensor, however, when the MCU 1 is a highperformance unit in which a program is developed in an external RAM andthe program can be executed at a higher speed as compared to a one-tipunit having a built-in RAM or the like, switching between the run stateand the sleep state can not be performed at a high speed, because aclock speed of the MCU 1 and that of the RAM are different, and it takestime for the both clocks to stabilize.

Further, the MCU 1 having high performance as described above requiresmore power consumption than a one-tip unit having a built-in RAM or thelike, so that it is not preferable from the viewpoint of power savingthat the high-performance MCU 1 is intermittently operated along with asensor to be activated from the sleep state only for executing sampling.

Thus the configuration is allowable in which, for instance, a one-tipunit for executing sampling of an output from a sensor is provided inthe information processing apparatus, in addition to a high-performanceMCU.

FIG. 19 is a block diagram showing still another example ofconfiguration of the information processing apparatus in which thepresent invention is applied.

In the information processing apparatus in FIG. 19 provided are a MainMCU 81 and a Sub MCU 82.

The Main MCU 81 develops a program stored in an external ROM to anexternal RAM, and executes the same. Further, the Main MCU 81 fetches asampling result for an output from the sensor 3 at a predeterminedtiming from the Sub MCU 82, and executes predetermined processingemploying the sampling result.

The Sub MCU 82 is, for instance, a one-tip unit having a built-in RAM orthe like. The Sub MCU 82 can perform switching between the run state andthe sleep state at a higher speed as compared to the Main MCU 81 withless power consumption. The Sub MCU 82 basically has the same functionsas those of the MCU 1 in FIG. 1.

Namely, the Sub MCU 82 carries out an intermittent operation along withthe sensor 3, controls supply of the power Vcc to the sensor 3 byswitching ON/OFF of the FET 2 in response to a signal outputted from aGPO terminal 91, and executes sampling of a signal supplied from thesensor 3 to a GPI terminal 12.

A sampling result by the Sub MCU 82 is stored in a buffer 93, and when apredetermined amount of sampling results is stored therein throughrepeated sampling, the stored sampling results are supplied via a busfrom the Sub MCU 82 to the Main MCU 81 in the mass.

Thus the Main MCU 81 does not need to restore from the sleep state everytime the Main MCU 81 carries out sampling of an output from the sensor,and only needs to restore just when the Main MCU 81 fetches a certainamount of the massed sampling results. The Main MCU 81 consumes morepower than the Sub MCU 82, so that power consumption of the entireinformation processing apparatus can be reduced by shortening anoperating time of such a unit consuming much power.

It is to be noted that the configuration is allowable in which a sensorconnected to the Sub MCU 82 is not limited to the sensor 3, but aplurality of sensors can be connected thereto as shown in FIG. 12. Whena plurality of sensors are connected to the Sub MCU 82, the Sub MCU 82executes processing as described above, namely, detecting the situationof the information processing apparatus based on an output from asensor, and controlling operations of other sensors based on thedetected result.

The processing performed by the Sub MCU 82 is described with referenceto the flow charts in FIG. 20 through FIG. 22. In this example, it isassumed that a plurality of sensors as shown in FIG. 12 are connected tothe Sub MCU 82. Further it is assumed that the Sub MCU 82 has theconfiguration as shown in FIG. 14.

In step S201, the situation detecting section 71 in the Sub MCU 82 (SeeFIG. 14) monitors a result of sampling sent from the sampling section 24and outputted from the humidity sensor 55.

In step S202, the situation detecting section 71 determines whether thehumidity has changed more than the threshold value for the change widthor not, and when it is determined that the humidity has changed morethan the threshold value for the change width, the situation detectingsection 71 goes to step S203, and reports via a bus to the Main MCU 81that movement in a space has been detected. The Main MCU 81 is keptactive at the minimum level so that a report from the Sub MCU 82 canalways be received.

When the humidity has changed largely, the possibility is high, forinstance, that a space in which the information processing apparatus isplaced has changed, namely that the information processing apparatus hasbeen moved, for instance, from a room to another room. Therefore, whenit is necessary to execute specific processing according to a result ofdetection concerning the movement, the Main MCU 81 is restored from thesleep state and executed the processing.

When it is determined that the humidity has largely changed, thesituation detecting section 71 outputs a signal indicating the change tothe power control section 21, for instance to start supply of the powerVcc to the illumination sensor 56 when the power Vcc is not supplied.

In step S204, the situation detecting section 71 monitors a result ofsampling for an output from the illumination sensor 56 sent from thesampling section 24, and then goes to step S205, and determines that theillumination is not less than a predetermined threshold value a or not.

When it is determined in step S205 that the illumination is not lessthan the threshold value a, the situation detecting section 71 outputs asignal indicating the fact to the power control section 21, and when thepower Vcc is not supplied, starts supply of the power Vcc to the UV raysensor 57.

In step S206, the situation detecting section 71 monitors a result ofsampling for an output from the UV ray sensor 57 sent from the samplingsection 24, goes to step S207, and determines whether a dose of UV raysis not less than a predetermined threshold value or not.

When it is determined in step S207 that a dose of UV ray is not lessthan the threshold value, the situation detecting section 71 goes tostep S208, and reports to the Main MCU 81 that the informationprocessing apparatus may have been removed to outdoors.

When a predetermined processing is required according to the fact thatthe information processing apparatus is currently outside a house, theMain MCU 81 is restored from the sleep state and executes the requiredprocessing.

In step S209, the situation detecting section 71 selects the GPS module51 as a device for positioning the information processing apparatus andoutput a signal indicating the selection to the power control section21, for instance, to start supply of the power Vcc to the GPS module 51if the power Vcc is not supplied thereto.

In step 210, the sampling section 24 carried out sampling for an outputfrom the GPS module 51 (for positioning), goes to step S211, and storesthe data indicated a result of positioning in a buffer 93 (Refer to FIG.19). When the information processing apparatus is outdoor, theprocessing in FIG. 20 is repeated and the data indicating record ofpositioning results in the buffer 93.

In step S212, the sampling section 24 determines whether a certainvolume of data (sampling result) has been stocked in the buffer 93 ornot, and when it is determined that a required volume of data has notbeen stocked therein, the processing is terminated. Then the processingin FIG. 20 is repeated with a predetermined cycle.

When it is determined in step S212 that a required volume of data hasbeen stocked, the sampling section 24 goes to step S213, and demands theMain MCU 81 to fetch the data stocked in the buffer 93 and terminatesthe processing. In response to this demand, the Main MCU 81 is restoredfrom the sleep state and fetches the data stocked in the buffer 93 via abus (step S234 in FIG. 24).

On the other hand, when it is determined in step S202 that the changerate of humidity is not larger than the threshold value, the situationdetecting section 71 goes to step S214 (Refer to FIG. 21). When thepower Vcc is not supplied, the situation detecting section 71 controlsthe power control section 21, and starts supply of the power Vcc to thegyro 53 as well as to the acceleration sensor 54.

In step S214, the situation detecting section 71 monitors a speedcompute from a result of sampling for outputs from the gyro 53 andacceleration sensor 54 sent from the sampling section 24, goes to step215, and determines whether the speed is not less than the thresholdvalue or not.

When it is determined that the speed is less than the predeterminedthreshold value, the situation detecting section 71 skips the processingsteps S216 and S217, and terminates the processing.

When it is determined in step S215 that the speed is not less than thepredetermined threshold value, the situation detecting section 71 goesto step S216, and determines whether the Main MCU 81 is active or not(in the sleep state or not).

When it is determined in step S216 that the main CMU 81 is active, thesituation detecting section 71 goes to step S217, and reports the speedobtained from the outputs from the gyro 53 and acceleration sensor 54 tothe Main MCU 81. Then the processing is terminated.

When it is determined in step S216 that the main CMU 81 is not active,the situation detecting section 71 goes to step S211, and stored thedata indicating the speed in the buffer 93, and executed the subsequentprocessing steps.

As described above, when a sampling result is obtained, determination ismade as to whether the Main MCU 81 is active or not, and when it isdetermined that the Main MCU 81 is active, the sampling result isimmediately reported, so that the Main MCU 81 can execute the processingwith high responsibility to a sampling result.

On the other hand, when it is determined in step S205 (FIG. 20) based ona result of monitoring the illumination that the detected illuminationis less than the threshold value a, the situation detecting section 71goes to step S218 (FIG. 22).

In step S218, the situation detecting section 71 determines whether thedetected illumination is less than the threshold value a and not lowerthan a threshold value b (a>b) or not, and when it is determined thatthe detected illumination is less than the threshold value a and notlower than the threshold value b, the situation detecting section 71goes to step S219, and makes the sampling section 24 execute high speedsampling for illumination.

By converting the illumination (shown along the time axis) to a value onthe frequency axis and by detecting a band to which the frequencyallowing the highest sensitivity belongs, the situation detectingsection 71 can determine whether the information processing apparatus isnow under solar light or under a fluorescent lamp.

In step S220, the situation detecting section 71 determines where thefrequency allowing the highest sensitivity is 100 Hz or 120 Hz.

A lighting apparatus such as a fluorescent lamp flickers at a frequencytwo times higher than a frequency of AD utility power (50/60 Hz), andtherefore the frequency of 100 Hz or 120 Hz allowing the highestfrequency indicates that the information processing apparatus iscurrently indoor. When the frequency allowing the highest sensibility isin the other frequency band, it indicates that the light source is thesun, namely that the information processing apparatus is outdoor.

Therefore, when it is determined in step S220 that the frequencyallowing the highest sensibility is not removing force measuring device100 Hz nor 120 Hz, the situation detecting section 71 goes to step S208,reports to the Main MCU 81 that the information processing apparatus iscurrently outdoor, and then executes the subsequent steps.

When it is determined in step S220 that the frequency allowing thehighest sensibility is removing force measuring device 100 Hz or 120 Hz,the situation detecting section 71 goes to step S221, and reports to theMain MCU 81 that the information processing apparatus is indoor. Alsowhen it is determined in step S207 shown in FIG. 20 that a dose of theUV ray is less than the threshold value, the situation detecting section71 reports the fact to the Main MCU 81.

When the high speed sampling for illumination in step S219 is to becarried out for a relatively long time, the sampling operation may becarried out intermittently as shown in FIG. 23.

In the example shown in FIG. 23, the time from the time point t₅₁ to thetime point t₅₃ is 10 seconds. In this case, the high speed sampling withthe frequency of 240 Hz is performed only for one second in the periodof time point t₅₁ to the time point t₅₂ to determine whether theinformation processing apparatus is indoor or outdoor.

When the Sub MCU 82 changes the operating state to the run state or thesleep state, the Sub MCU 82 also turns ON or OFF the power Vcc for theillumination sensor 56, and enter the sleep state at the time point t₅₂and on.

As a light source does not change so quickly, a change in the situationcan be detected by the intermittent sampling as described above. Furtherwhile high speed sampling is being executed, a work load to the Sub MCU82, and also a consumed power increases, so that the period of timeshould preferably be as short as possible.

Again in FIG. 22, the situation detecting section 71 reports to the MainMCU 81 that the information processing apparatus is indoor, and then instep S222, selects the PHS module 52 as a device for positioning theinformation processing apparatus, and controls the power control section21, for instance, to start supply of the power Vcc to the PHS module 52.Further when the power Vcc to the GPS module 51 is supplied, thesituation detecting section 71 terminates the power supply.

In step S223, the sampling section 24 performs sampling for an outputfrom the PHS module 52, goes to step S211, stores the positioning resultin the buffer 93, and then executes the subsequent processing steps.

As described above, by using the sensors according to the currentsituation, namely, for instance, by using the PHS module 52 indoor, as apositioning device when the information processing apparatus is indoor,and the GPS module 51 when the information processing apparatus isoutdoor, positioning can be executed accurately.

On the other hand, when it is determined in step S218 that the detectedillumination is less than the threshold value b, the situation detectingsection 71 goes to step S224 and monitors a result of sampling for anoutput from the humidity sensor 55 supplied from the sampling section24.

In step S225, the situation detecting section 71 determines whether thechange rate in the humidity is larger than a width indicated by athreshold value or not. In step S225, the situation detecting section 71determines that the humidity has largely changed, goes to step S226,controls the power control section 21 to supply the power Vcc to the GPSmodule Vcc for positioning with the GPS module 51.

In step S227, the situation detecting section 71 determines based on anoutput from the sampling section 24, whether a predetermined period oftime is over or not, namely whether the GPS module 51 has succeeded inacquiring the satellite or not.

When it is determined in step S227 that the predetermined period of timeis over, the situation detecting section 71 goes to step S221, reportsto the Main MCU 81 that the information processing apparatus is indoor,and on the contrary, when it is determined that the predetermined periodof time is not over, namely that the satellite has been caught, thesituation detecting section 71 goes to step S208 (FIG. 20), and reportsto the Main MCU 81 that the information processing apparatus is outdoor.Then the processing steps in step S221 and one, or in step S209 and onare executed.

Next, the processing by the Main MCU 81 executed in response to theprocessing steps shown in FIG. 20 through FIG. 22 is described.

In step S231, the Main MCU 81 in the sleep state receives a report fromthe Sub MCU 82 (for instance a report concerning the steps S203, S208shown in FIG. 20, or a demand in step S213).

In step S232, the Main MCU 81 determines whether the received report isa demand for acquisition of a sampling result (the demand in step S213shown in FIG. 20) or not, and when it is determined that the receivedreport is not the demand as described above, the MCU 81 terminates theprocessing.

On the other hand, when it is determined in step S232 that the receivedreport is a demand for acquisition of a sampling result, the Main MCU 81goes to step S233, and is restored from the sleep state.

After the Main MCU81 is restored from the sleep state, in step S234, theMain MCU 81 fetches data indicating a sampling result stored in thebuffer 93 of the Sub MCU 82 via a bus, and executes a predeterminedprocessing step based on the sampling result.

As described above, by making the Sub MCU 82 consuming a power lessexecute sampling for outputs from the sensors, controlling supply of thepower Vcc to the sensors based on the situation under which aninformation processing apparatus is placed, and provide a certain volumeof sampling results to the Main MCU 81 in batch, it is possible toshortening a operating time of the Main MCU 81 consuming a power much,so that the power consumption in the entire device can be reduced.

The configuration shown in FIG. 19 in which the Main MCU 81 and the SubMCU 82 are prepared in one information processing apparatus may beemployed only when, for instance, a sensor executing sampling with ashort cycle is prepared as the sensor 3. When a sensor operating with along cycle is prepared as the sensor 3, the state transitioncorresponding to the sampling cycle can be realized by the Main MCU 81.

In the description above, it is assumed that the PHS module 52 is usedas a positioning device when the information processing apparatus isindoor, but positioning by the PHS module 52 is carried out based oninformation from a base station transmitting electric waves which thePHS module 52 receives, and the precision is worse than that inpositioning by the GPS module 51, and is about 400 m.

Therefore, in this case, like in the case of the GPS module 51 (with theprecision of 20 m) described above, when it is determined based on thespeed obtained from an output from the gyro 53 or the accelerationsensor 54 that a travel of the information processing apparatus within apositioning cycle is not more than 400 m, the power Vcc is not suppliedto the PHS module 52, and when the travel is over 400 m, the power Vccmay be supplied to the PHS module 52.

Further it is needless to say that the PHS module 52 may be usedoutdoors. In this case, in order to activate the PHS module 52 only whenaccurate positioning is possible, supply of the power Vcc to the PHSmodule 52 may be stopped when it is determined based on an output fromthe gyro 52 or acceleration sensor 54 that the PHS module 52 is movingat a speed of, for instance, 80 km or more.

As described above, various modes of control other than that shown inFIG. 12 may be employed for controlling other sensors according to thesituation.

For instance, by controlling operation of a CCD (Charge Coupled Device)so that a shutter speed of a CCD is made faster, it is possible to pickup an image with little blurring.

On the other hand, when it is determined based on an output from theacceleration sensor that the PHS module 52 moves little, by controllingoperations of the CCD so that the shutter speed is made slower, it ispossible to secure a sufficient quantity of light.

Further the state transition as shown in FIG. 2 or FIG. 8 can berealized with the MCU 1 shown in FIG. 12 or by the Sub MCU 82 shown inFIG. 19.

Although the operation sequence described above may be executed byhardware, the operation sequence may be executed with software. In thiscase, a device used for running the software includes, for instance, apersonal computer as shown in FIG. 25.

In FIG. 25, a CPU (Central Processing Unit) 101 executes various typesof processing according to programs stored in a ROM 102 or loaded from astorage section 108 into a RAM 103. Also data required for execution ofvarious types of processing by the CPU 101 is stored in the RAM 103according to the necessity.

The CPU 101, ROM 102, and RAM 103 are connected to each other via a bus104. Also an input/output interface 105 is connected to this bus 104.

Connected to the input/output interface 105 are an input section 106including a keyboard and a mouse, a display including an LCD or thelike, and an output section 107 including a speaker or the like, astorage section 108 including a hard disk or he like, and acommunicating section 109 for executing processing for communication viaa network.

Also a drive 110 may be connected to the input/output interface 105 withsuch devices as a magnetic disk, an optical disk, a magnetic opticaldisk, or a semiconductor memory incorporated thereon according to thenecessity, and a computer program read out therefrom is installed in thestorage section 108.

When the operation sequence is executed by software, a program orprograms each constituting the software is installed from the network ora recording medium into, for instance, a computer incorporated in thededicated hardware, or a general purpose personal computer capable ofexecuting various types of functions when required programs areinstalled therein.

This recording medium may include, as shown in FIG. 25, not only amagnetic disk (including a flexible disk), an optical disk (CD-ROM(Compact Disk-Read Only Memory), and a DVD (including Digital VersatileDisk)), a magnetic optical disk (including MD (Registered trade mark)(Mini-Disk)) each with a program recorded therein distributed to providethe program to a user, or a removable media 111 including asemiconductor memory or the like, but also a ROM 102 with the programrecorded therein, or a hard disk included in the storage section 108.

The processing steps described in this specification include not onlythose executed according to the order described therein or sequentially,but also those which are not always executed sequentially and executedconcurrently or discretely.

The term “system” as used herein indicates an entire apparatus includinga plurality of devices.

1. An information processing apparatus comprising: a plurality ofdetection units each for detecting a physical quantity as a target fordetection; and a control unit for measuring the physical quantity basedon a result of detection by one or more first detection units among theplurality of detection units and also controlling supply of a power to asecond detection unit in response to a result of measurement of thephysical quantity.
 2. The information processing apparatus according toclaim 1, wherein the control unit measures, when supply of a power tothe second detection unit is started, the physical quantity based on aresult of detection by the second detection unit.
 3. The informationprocessing apparatus according to claim 1, wherein the first detectionunit consumes a power less as compared to the second detection unit. 4.The information processing apparatus according to claim 1, wherein thecontrol unit controls supply of a power to the second detection unitbased on the priority of the second detection unit set according to aresult of measurement of the physical quantity.
 5. The informationprocessing apparatus according to claim 4, wherein the control unitdetermines its own operating situation from a result of detection by thefirst detection unit and sets the priority of the second detection unitso that higher priority is set for the second detection unit morerequired to be operated in the determined situation.
 6. The informationprocessing apparatus according to claim 4, wherein the second detectionunit comprises a first positioning unit for executing positioningoutdoors, and a second positioning unit for executing positioningindoors; and the control unit sets, when it is determined from a dose ofultraviolet rays measured based on a result of detection by the firstdetection unit that the control unit is present outdoors, higherpriority to the first positioning unit as compared to that to the secondpositioning unit, and controls supply of a power to the first and secondpositioning units so that positioning is executed only by the firstpositioning unit.
 7. The information processing apparatus according toclaim 6, wherein the control unit controls supply of a power to thefirst and second positioning units so that positioning is executed onlywhen a distance obtained by multiplying a speed measured based on aresult of detection by the first detection unit by a cycle ofpositioning by the first or second positioning unit shows higherprecision as computed to that in positioning by the first or secondpositioning unit.
 8. The information processing apparatus according toclaim 6, wherein the control unit controls supply of a power to thefirst positioning unit so that positioning is executed by the firstpositioning unit when a change in humidity measured based on a result ofdetection by the first detection unit is over a predetermined thresholdvalue.
 9. The information processing apparatus according to claim 1,wherein the first detection unit includes a first positioning unit formeasuring illumination intensity and a second measuring unit formeasuring a dose of ultraviolet rays; and the control unit controlssupply of a power to the second measuring unit so that measurement of adose of ultraviolet rays is executed by the second measuring unit whenillumination intensity over the predetermined threshold value ismeasured by the first measuring unit.
 10. The information processingapparatus according to claim 1 further comprising: a storage unit forstoring therein a period of time after measurement of a physicalquantity by the control unit based on a result of detection by a thirddetection unit among the plurality of detection units is finished untilmeasurement of the physical quantity is executed next as a standbyperiod with the control unit shifted to the standby state during theperiod, wherein the control unit repeats the processing for startingsupply of a power to the third detection unit and measuring the physicalquantity based on a result of detection by the third detection unit andthe processing for stopping supply of a power to the third detectionunit, shifting its own state to the standby state, and returning fromthe standby state after passage of the standby period.
 11. Theinformation processing apparatus according to claim 1 furthercomprising: a storage unit for storing therein a period of time aftersupply of a power to a third detection unit among the plurality ofdetection units is started until a normal result of detection by thethird detection unit is obtained as a standby period with the controlunit shifted to the standby state during the period, wherein the controlunit further starts supply of a power to the third detection unit,shifts its own state to the standby state, returns from the standbystate after passage of the standby period, and measures the physicalquantity based on a result of detection by the third detection unit. 12.The information processing apparatus according to claim 1 furthercomprising: a storage unit for storing therein data indicating thephysical quantity measured by the control unit, wherein the control unitsupplies, when a predetermined volume of data indicating the physicalquantity is stored by the storage unit, the predetermined volume of dataindicating the physical quantity is supplied to other control unitexecuting a predetermined processing.
 13. An information processingmethod executed by an information processing apparatus including aplurality of detection units each for detecting a physical quantity as atarget for detection, comprising the step of providing controls formeasuring the physical quantity based on a result of detection by one ormore first detection units among the plurality of detection units andalso controlling supply of a power for a second detection unit accordingto a result of measurement of the physical quantity.
 14. A program to beexecuted by a computer for controlling an information processingapparatus including a plurality of detection units each for detecting aphysical quantity as a target for detection, comprising the step of:providing controls for measuring the physical quantity based on a resultof detection by one or more first detection units among the plurality ofdetection units and also controlling supply of a power for a seconddetection unit according to a result of measurement of the physicalquantity.